Adaptation of a Chlamydomonas mutant with reduced rate of photorespiration to different concentrations of CO2

2005 ◽  
Vol 83 (7) ◽  
pp. 834-841 ◽  
Author(s):  
Kensaku Suzuki ◽  
Hidenori Onodera
Keyword(s):  
Chlorophyll Fluorescence ◽  
Chlamydomonas Reinhardtii ◽  
Inorganic Carbon ◽  
Electron Flow ◽  
Effective Quantum Yield ◽  
Wild Type ◽  
Chlorophyll Fluorescence Parameters ◽  
Phosphoglycolate Phosphatase ◽  
Concentrating Mechanism ◽  
Type Strains

It has been widely accepted that Chlamydomonas reinhardtii cells utilize inorganic carbon very efficiently for photosynthesis by operating a CO2-concentrating mechanism (CCM) under conditions of limited CO2. To help define the mechanism, 7FR2N, one of the suppressor double mutants of phosphoglycolate phosphatase-deficient (pgp1) mutants that have a reduced photorespiration rate (RPR) was crossed with wild-type strains to generate the strain N21 as a single RPR mutant. The comparison of photosynthetic characteristics with wild-type strains after the cells adapted to different concentrations of CO2 revealed that photosynthetic affinity for inorganic carbon was higher than that in wild-type strains after adaptation to concentrations between 50 µL·L–1 CO2 and 5% CO2. Chlorophyll fluorescence parameters were also compared, and the biggest difference between N21 and the wild-type strains was observed in the photochemical quenching and effective quantum yield of photosystem II (ΔF/Fm′) at the CO2 compensation point. These values in N21 increased in a similar manner to the photosynthetic affinity for CO2, and increased significantly when the cells adapted to low-CO2 levels, whereas the values in the wild-type strains were apparently lower without any significant changes, regardless of the CO2 concentrations to which they were adapted. Although it was not clear if a nonphotochemical quenching parameter (NPQ) in N21 was higher than that in wild-type strains, NPQ increased coincidentally with the increase in photosynthetic affinity for inorganic carbon when the CO2 concentrations to which the strains were adapted decreased, in both the mutant and wild-type strain, suggesting that this form of NPQ reflects the operation of CCM in certain conditions. Possible candidates for the RPR mutation and the relationship between CCM and photosynthetic electron flow are discussed.Key words: Chlamydomonas reinhardtii, chlorophyll fluorescence, CO2-concentrating mechanism, low-CO2 responsive gene, phosphoglycolate phosphatase, photorespiration.

scholarly journals Condensation of Rubisco into a proto-pyrenoid in higher plant chloroplasts

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicky Atkinson ◽  
Yuwei Mao ◽  
Kher Xing Chan ◽  
Alistair J. McCormick
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Recent Work ◽  
Single Phase ◽  
Inorganic Carbon ◽  
Higher Plants ◽  
Initial Step ◽  
Operating Efficiency ◽  
Higher Plant ◽  
Spontaneous Condensation ◽  
Concentrating Mechanism

AbstractPhotosynthetic CO2 fixation in plants is limited by the inefficiency of the CO2-assimilating enzyme Rubisco. In most eukaryotic algae, Rubisco aggregates within a microcompartment known as the pyrenoid, in association with a CO2-concentrating mechanism that improves photosynthetic operating efficiency under conditions of low inorganic carbon. Recent work has shown that the pyrenoid matrix is a phase-separated, liquid-like condensate. In the alga Chlamydomonas reinhardtii, condensation is mediated by two components: Rubisco and the linker protein EPYC1 (Essential Pyrenoid Component 1). Here, we show that expression of mature EPYC1 and a plant-algal hybrid Rubisco leads to spontaneous condensation of Rubisco into a single phase-separated compartment in Arabidopsis chloroplasts, with liquid-like properties similar to a pyrenoid matrix. This work represents a significant initial step towards enhancing photosynthesis in higher plants by introducing an algal CO2-concentrating mechanism, which is predicted to significantly increase the efficiency of photosynthetic CO2 uptake.

scholarly journals Protective Effects of Selenium on Wheat Seedlings under Salt Stress

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 272 ◽  
Author(s):  
Chiu-Yueh Lan ◽  
Kuan-Hung Lin ◽  
Wen-Dar Huang ◽  
Chang-Chang Chen
Keyword(s):  
Salt Stress ◽  
Chlorophyll Fluorescence ◽  
Energy Dissipation ◽  
Quantum Yield ◽  
Photosystem Ii ◽  
Physiological Traits ◽  
Effective Quantum Yield ◽  
Enzymatic Antioxidants ◽  
Wheat Seedlings ◽  
Chlorophyll Fluorescence Parameters

Wheat is a staple food worldwide, but its productivity is reduced by salt stress. In this study, the mitigative effects of 22 μM selenium (Se) on seedlings of the wheat (Triticum aestivum L.) cultivar Taichung SEL. 2 were investigated under different salt stress levels (0, 100, 200, 300, and 400 mM NaCl). Results of the antioxidative capacity showed that catalase (CAT) activity, non-enzymatic antioxidants (total phenols, total flavonoids, and anthocyanins), 1,1-Diphenyl-2-Picryl-Hydrazyl (DPPH) radical-scavenging activity, and the reducing power of Se-treated seedlings were enhanced under saline conditions. The more-stabilized chlorophyll fluorescence parameters (maximal quantum yield of photosystem II (Fv/Fm), minimal chlorophyll fluorescence (F0), effective quantum yield of photosystem II (ΦPSII), quantum yield of regulated energy dissipation of photosystem II (Y(NPQ)), and quantum yield of non-regulated energy dissipation of photosystem II (Y(NO)) and the less-extensive degradation of photosynthetic pigments (total chlorophyll and carotenoids) in Se-treated seedlings were also observed under salt stress. The elongation of shoots and roots of Se-treated seedling was also preserved under salt stress. Protection of these physiological traits in Se-treated seedlings might have contributed to stable growth observed under salt stress. The present study showed the protective effect of Se on the growth and physiological traits of wheat seedlings under salt stress.

Temperature optima for growth and photosynthetic processes in Trebouxia erici isolated from an Antarctic lichen and cultivated in a temperature gradient

2017 ◽  
Vol 7 (1) ◽  
pp. 34-44 ◽  
Author(s):  
Timm Bayer ◽  
Nıevas Vıals Alba
Keyword(s):  
Chlorophyll Fluorescence ◽  
Natural Populations ◽  
Effective Quantum Yield ◽  
Ps Ii ◽  
Chlorophyll Fluorescence Parameters ◽  
Different Temperatures ◽  
Chlorophyll Production ◽  
Time Courses ◽  
Temperature Optima

The temperature optimum for photosynthesis and growth of natural populations of Trebouxia erici isolated from an Antarctic lichen (Usnea antarctica) was determined using a long-term cultivation (26 days) at different temperatures. Several chlorophyll fluorescence parameters were used in T. erici cultivated in a liquid medium to assess the effect of cultivation temperature (0, 10, 20 and 30oC). Analysis of time courses of the capacity of photosynthetic processes in PS II (FV/FM), effective quantum yield of photosystem II (FPSII), relative fluorescence decline ratio (RFd), and quenching of background chlorophyll fluorescence (qF0) revealed that optimum temperature is between 10 to 20°C. Biomass production evaluated as a total chlorophyll production after 26 days of cultivation was maximal at 20°C. The results are discussed in relation to the data reported by other literature sources for Trebouxia sp. and other algae isolated from chlorolichens.

scholarly journals Effect of Drought Stress on Chlorophyll Fluorescence Parameters, Phytochemical Contents, and Antioxidant Activities in Lettuce Seedlings

Horticulturae ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 238
Author(s):  
Yu Kyeong Shin ◽  
Shiva Ram Bhandari ◽  
Jung Su Jo ◽  
Jae Woo Song ◽  
Jun Gu Lee
Keyword(s):  
Ascorbic Acid ◽  
Chlorophyll Fluorescence ◽  
Drought Stress ◽  
Quantum Yield ◽  
Antioxidant Activities ◽  
Growth Parameters ◽  
Photochemical Quenching ◽  
Total Phenol Content ◽  
Effective Quantum Yield ◽  
Chlorophyll Fluorescence Parameters

This study monitored changes in chlorophyll fluorescence (CF), growth parameters, soil moisture content, phytochemical content (proline, ascorbic acid, chlorophyll, total phenol content (TPC), and total flavonoid content (TFC)), and antioxidant activities in 12-day-old lettuce (Lactuca sativa L.) seedlings grown under drought stress (no irrigation) and control (well irrigated) treatments in controlled conditions for eight days. Measurements occurred at two-day intervals. Among ten CF parameters studied, effective quantum yield of photochemical energy conversion in PSII (Y(PSII)), coefficient of photochemical quenching (qP), and coefficient of photochemical quenching of variable fluorescence based on the lake model of PSII (qL) significantly decreased in drought-stressed seedlings from day 6 of treatment compared to control. In contrast, maximum quantum yield (Fv/Fm), ratio of fluorescence (Rfd), and quantum yield of non-regulated energy dissipation in PSII (Y(NO)) were significantly affected only at the end. All growth parameters decreased in drought-stressed seedlings compared to control. Proline started increasing from day 4 and showed ~660-fold elevation on day 8 compared to control. Chlorophyll, ascorbic acid, TPC, TFC, and antioxidant activities decreased in drought-stressed seedlings. Results showed major changes in all parameters in seedlings under prolonged drought stress. These findings clarify effects of drought stress in lettuce seedlings during progressive drought exposure and will be useful in the seedling industry.

scholarly journals Comparative research of photosynthetic processes in selected poikilohydric organisms from Mediterranean and Central-European alpine habitats

2018 ◽  
Vol 8 (2) ◽  
pp. 286-298
Author(s):  
Gabriella Nora Maria Giudici ◽  
Josef Hájek ◽  
Miloš Barták ◽  
Svatava Kubešová
Keyword(s):  
Czech Republic ◽  
Chlorophyll Fluorescence ◽  
Photochemical Quenching ◽  
Marchantia Polymorpha ◽  
Effective Quantum Yield ◽  
Response Curves ◽  
Chlorophyll Fluorescence Parameters ◽  
Fluorescence Parameters ◽  
Mediterranean Habitats ◽  
Non Photochemical Quenching

Dehydration-induced decrease in photosynthetic activity was investigated in five poikilohydric autotrophs using chlorophyll fluorescence parameters recorded during controlled desiccation. For the study, two representatives of mosses from alpine zone (Rhizomnium punctatum, Rhytidiadelphus squarrosus) of the Jeseníky Mts. (Czech Republic) were used. Other two experimental species were mediterranean habitats liverwort (Pellia endiviifolia) and moss (Palustriella commutata), collected from under Woodwardia radicans canopy in the Nature Reserve Valle delle Ferriere (Italy). The last species was a liverwort (Marchantia polymorpha) collected from lowland site (Brno, Moravia, Czech Republic). We investigated the relationship between relative water content (RWC) and several chlorophyll fluorescence parameters evaluating primary photochemical processes of photosynthesis, such as effective quantum yield of photosynthetic processes in photosystem II (ΦPSII), and non-photochemical quenching (qN). With desiccation from fully wet (RWC = 100%) to dry state (RWC = 0%), ΦPSII exhibited a rapid (R. punctatum) and slow decline of ΦPSII (R. squarrosus, P. endiviifolia, M. polymorpha, and P. commutata). Shapes of dehydration-response curves were species-specific. RWC0.5, i.e. the RWC at which the sample showed half of maximum ΦPSII, reflected the species-specificity. It reached 65% in desiccation sensitive (R. punctatum), 53% and 43% in semi-tolerant (P. commutata and R. squarrosus), 24% and 18% in desiccation-tolerant species (P. endiviifolia and M. polymorpha). In all experimental species, non-photochemical quenching (qN) of absorbed light energy showed high values at RWC = 100% and a slight increase with desiccation. Steady state chlorophyll fluorescence (FS) remained high during desiccation and was not correlated with ΦPSII.  

Enhanced sensitivity of Arabidopsis anthocyanin mutants to photooxidation: a study with fluorescence imaging

2008 ◽  
Vol 35 (8) ◽  
pp. 714 ◽  
Author(s):  
Ling Shao ◽  
Zhan Shu ◽  
Chang-Lian Peng ◽  
Zhi-Fang Lin ◽  
Cheng-Wei Yang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Chlorophyll Fluorescence ◽  
Fluorescence Imaging ◽  
Photosynthetic Apparatus ◽  
Chlorophyll Fluorescence Imaging ◽  
Prolonged Treatment ◽  
Partial Recovery ◽  
Wild Type ◽  
Short Term Treatment ◽  
Chlorophyll Fluorescence Parameters

Chlorophyll fluorescence imaging and antioxidative capability in detached leaves of the wild-type Arabidopsis thaliana ecotype Landsberg erecta (Ler) and in three mutants deficient in anthocyanin biosynthesis (tt3, tt4 and tt3tt4) were investigated under photooxidation stress induced by methyl viologen (5 μm) in the light. In comparison with the wild-type (WT) plant, photooxidation resulted in significant decreases in the contents of total phenolics and flavonoid, total antioxidative capability and chlorophyll fluorescence parameters (Fv/Fm, qP, ΦPSII, NPQ and ETR) as determined by chlorophyll fluorescence imaging, and in an increase in cell-membrane leakiness in the three anthocyanin mutants. The sequence of sensitivity to photooxidation in the leaves of the four phenotypes were tt3tt4 (deficient in both chalcone synthase locus (CHS) and dihydroflavonol 4-reductase locus (DFR)) > tt4 (deficient in CHS) > tt3 (deficient in DFR) > WT. The results demonstrate that anthocyanins might, along with other antioxidants, protect the photosynthetic apparatus against photooxidative damage. An interesting phenomenon was observed over the 270 min of the photooxidative treatment, that is, fluorescence imaging revealed that qP, ΦPSII and ETR appeared in three phases (fall → partial recovery → rapid fall). This was considered to be a modulation of reversible deactivation in PSII to cope with the moderate oxidative stress in the first two stages of short-term treatment (<150 min), followed finally by damage to PSII under severe oxidative stress with prolonged treatment.

A mutant of Chlamydomonas reinhardtii that cannot acclimate to low CO2 conditions has an insertion in the Hdh1 gene

2005 ◽  
Vol 32 (1) ◽  
pp. 55 ◽  
Author(s):  
James E. Adams ◽  
Sergio L. Colombo ◽  
Catherine B. Mason ◽  
Ruby A. Ynalvez ◽  
Baran Tural ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Inorganic Carbon ◽  
Single Copy ◽  
Wild Type ◽  
Poor Growth ◽  
Altered Expression ◽  
Haloacid Dehalogenase ◽  
Low Co2 ◽  
Photosynthetic Microorganisms ◽  
Zeocin Resistance

Photosynthetic microorganisms must acclimate to environmental conditions, such as low CO2 environments or high light intensities, which may lead to photo-oxidative stress. In an effort to understand how photosynthetic microorganisms acclimate to these conditions, Chlamydomonas reinhardtii was transformed using the BleR cassette, selected for Zeocin resistance and screened for colonies that showed poor growth at low CO2 levels. One of the insertional mutants obtained, named slc-230, was shown to have a BleR insert in the first exon of Hdh1, a novel, single copy gene. The predicted Hdh1 gene product has similarity to bacterial haloacid dehalogenase-like proteins, a protein family that includes phosphatases and epoxide hydrolases. In addition, Hdh1 is predicted to be localised to the chloroplast or mitochondria in C. reinhardtii. It was found that a genomic copy of wild type Hdh1 can complement slc-230. Physiological studies were conducted to determine the effects of the altered expression of Hdh1 in slc-230. slc-230 grows slowly autotrophically in low CO2, exhibits a lower affinity for inorganic carbon, a decreasing photosynthetic rate over time and a lower content of chlorophylls and quenching xanthophylls than wild type cells. Some possible roles of Hdh1 in the acclimation to low CO2 conditions are discussed.

scholarly journals The Adaptive Ability of Cornus Stolonifera Michx. ´Kelseyi´ in Changing Environment

2014 ◽  
Vol 17 (1) ◽  
pp. 20-23
Author(s):  
Daniela Bartošová Krajčovičová ◽  
Viera Šajbidorová
Keyword(s):  
Chlorophyll Fluorescence ◽  
Chlorophyll A ◽  
Effective Quantum Yield ◽  
Water Efficiency ◽  
Chlorophyll Fluorescence Parameters ◽  
Chlorophyll Fluorescence Quenching ◽  
Cornus Stolonifera ◽  
Substrate Saturation ◽  
Fluorescence Of Chlorophyll A ◽  
Adaptive Ability

Abstract Water represents one of the limiting environmental factors having impact on all the processes in plants. Water stress is considered as the most significant cause of photosynthesis defects. Measuring fluorescence of chlorophyll a is one of the methods revealing defects in the photosynthetic aparatus. The examination has been carried out on the plants Cornus stolonifera Michx. ´KELSEYI´ cultivated in two different irrigation regimes (a regime with 40% substrate saturation and a controlling regime with 60% substrate saturation). We have used a fluorometer HANSATECH FMS 1 to measure modulated fluorescence of chlorophyll a. A three-week period of measurement was set between June and August during two years of experiments (2011 and 2012). The selected chlorophyll fluorescence parameters Fv /Fm - maximum quantum efficiency of PSII; ΦPSII - effective quantum yield of PSII; Rfd - chlorophyll fluorescence decrease ratio and NPQ - non-photochemical chlorophyll fluorescence quenching, proved to be insensitive to given water deficit. Cornus stolonifera Michx. ´KELSEY´ appears to be a woody plant capable of water efficiency.

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